package test.sachi.dsnalgos;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.NoSuchElementException;
import java.util.Queue;
/*
* Create two queues : 'q' and 'tmpq' as in the program given below
For push operation :
if size of q = 0 then
enqueue value into q
else
dequeue all elements from q to tmpq
enqueue value into q
dequeue all elements from tmpq to q
For pop operation :
if size of q = 0 then
throw 'underflow' exception
else
return front element of q
*/
public class StackUsingTwoQueues {
Queue<Integer> q;
Queue<Integer> tempq;
// contructor
public StackUsingTwoQueues() {
q = new LinkedList<Integer>();
tempq = new LinkedList<Integer>();
}
// Method to push the element to the Stack
public void push(int data) {
if (q.size() == 0) {
q.add(data);
} else {
int l = q.size();
for (int i = 0; i < l; i++) {
tempq.add(q.remove());
}
q.add(data);
for (int i = 0; i < l; i++) {
q.add(tempq.remove());
}
}
}
public int pop() throws Exception {
if (q.size() == 0) {
throw new NoSuchElementException("Underflow Exception");
}
return q.remove();
}
public int peek() throws Exception {
if (q.size() == 0) {
throw new NoSuchElementException("Underflow Exception");
}
return q.peek();
}
public boolean isEmpty(){
if(q.size()==0){
return true;
}else{
return false;
}
}
public int getSize(){
return q.size();
}
public void display(){
System.out.print("\nStack = ");
int l = getSize();
if (l == 0)
System.out.print("Empty\n");
else
{
Iterator<Integer> it = q.iterator();
while (it.hasNext())
System.out.print(it.next()+" ");
System.out.println();
}
}
}
